The H2O impedance measurement is a variant of tympanometry in which the middle ear pressure-volume behavior is examined with a water-filled ear canal. Controlled pressure changes are used to assess the mobility of the eardrum and ossicular chain. Deviations in the impedance curve indicate tube dysfunction, effusions or stiffening (e.g. otosclerosis). As water has a different acoustic resistance to air, this method provides greater sensitivity for small leaks and membrane damage. Clinically, it is mainly used in pediatric audiology and veterinary diagnostics.

Habituation refers to the diminishing reaction to repeatedly presented, unchanged stimuli. In the auditory system, it leads to constant background noise being faded out over time. This mechanism protects against information overload and makes it possible to focus on new, relevant signals. Habituation is used in tinnitus therapy to reduce the awareness of ear noises. If habituation is lacking, hypersensitivity and increased cognitive stress arise due to constant noise perception.

The sharkbone pattern in the audiogram describes alternating high and low points along the curve, similar to the teeth of a shark's tooth. It indicates measurement artifacts, lack of concentration or simulated hearing loss. Clinically, it is important to recognize this pattern in order to ensure valid findings and avoid misdiagnosis. If non-organic hearing loss is suspected, objective tests such as OAE or AEP follow. Cleaning the test environment and providing clear instructions to the patient reduce sharkbone artifacts.

The reverberation effect describes the phenomenon that a sound is perceived longer in a room with reverberation than in an anechoic chamber. Psychoacoustically, reverberation leads to an increase in level and distortion of the temporal structure of speech signals. Reverberation separation must be taken into account when fitting hearing aids in order to maintain speech intelligibility in real rooms. Reverberation time measurements (RT60) provide parameters for room acoustic optimization. Training programs teach listeners to distinguish between direct and reflected sound components.

The malleus is the first of the three auditory ossicles in the middle ear and is directly connected to the eardrum. It mechanically transmits vibrations from the eardrum to the anvil and thus controls the transport of sound into the inner ear. Its lever effect amplifies the sound pressure and enables efficient impedance matching between the air and fluid medium. The hammer reflex, triggered by loud sounds, protects against excessive sound damage. In surgery, care is taken to preserve the malleus structures so as not to impair sound conduction.

The hammer-anvil reflex is a muscle contraction of the tensor tympani and stapedius in response to loud noises, which stiffens the ossicular chain. This dampens vibrations and protects the inner ear from noise damage. Reflex latency and amplitude are measured in tympanometry to assess middle ear and brainstem function. Unilateral deficits indicate nerve lesions or ossicular pathologies. The reflex contributes to acoustic adaptation and shields against impulse sound.

A handheld microphone is an external microphone held by speakers in FM or DECT systems to transmit speech directly to hearing aid receivers. It improves speech intelligibility in noisy or large rooms as ambient noise is not picked up. Direct transmission minimizes signal loss and improves signal-to-noise ratio. Receivers in the hearing aid decode the radio signal and transmit it to the receiver. Hand-held microphones are essential in classrooms, conferences and religious events.

A home device is a hearing system that offers programs specially optimized for use at home, e.g. for television or telephony. This category often includes desktop or near-field communication devices with direct hearing aid coupling. They offer higher amplification and special filters to clearly transmit distant or digital sound sources. Home devices complement mobile hearing aid care and increase comfort in the home environment. Integration with smart home systems enables automatic scene selection.

Skin conduction (also known as structure-borne sound conduction) transmits vibrations via soft tissue and bone directly to the inner ear, bypassing the outer ear and middle ear. It plays a role in hearing one's own voice (autophony) and in bone conduction hearing systems. Skin conduction measurements help to distinguish conductive from sensorineural hearing loss. Bone conduction devices use sound cuvettes or implants to specifically stimulate this pathway. Skin conduction levels are less frequency dependent than air conduction.

BTE (behind-the-ear) hearing aid sits behind the pinna and connects to an earmold in the ear canal via a tube. It offers space for larger amplifiers, batteries and multi-channel signal processors. BTE systems are powerful and suitable for moderate to severe hearing loss. Modern models feature wireless networking, directional microphones and rechargeable batteries. The design enables easy handling and robust electronics.

The HRTF describes the frequency-dependent filter effect of the head, torso and auricles on incoming sound waves. It forms the basis for spatial hearing and virtual audio rendering, as it encodes interaural time and level differences. Measurements are made using microphones in artificial heads or individual calibration methods. In hearing aid development, HRTF models are used to obtain natural localization even with devices behind the ear. VR and 3D audio technologies are based on HRTF synthesis for immersive sound experiences.

The healing phase after eardrum perforation or middle ear surgery includes the initial inflammatory reaction, new tissue formation and scarring. In the first few days, the focus is on pain and infection control, followed by tissue remodeling over a period of weeks. Tympanometry and otoscopy monitor the reclosure and function of the eardrum. Hearing improvement is gradual, full recovery can take months. Physical rest and avoidance of pressure changes support healing.

The helix is the upper, curved edge of the pinna and is used to focus sound into the cavum conchae. Its shape influences the spectral filtering of external sound and supports vertical localization. Anatomical variations of the helix can shape individual HRTF profiles. In hearing aid fitting, attention is paid to helix compatibility in order to avoid pressure points. Surgically, the helix plays a role in earmolds and reconstructions.

A Helmholtz resonator is an acoustic resonator consisting of a cavity and a narrow opening that strongly amplifies sound at its natural frequency. In the ear, the cavum conchae has a similar effect and emphasizes frequencies around 2-5 kHz, which promotes speech comprehension. Acoustic filters in hearing aids use the Helmholtz principle for compact bass attenuation or notch filters against tinnitus frequencies. Room acoustic elements such as bass traps work according to the same physical principle.

The comfort threshold is the level at which sound is perceived as unpleasantly loud. With hearing loss, this threshold often shifts upwards, which means that those affected later find loud stimuli annoying. Hearing aid compression must take the comfort threshold into account in order to avoid overmodulation. Measurements using Bekesy audiometry or loudness scaling determine individual comfort ranges. Fine adjustment protects against discomfort and distortion.

Heterophonic masking occurs when an interfering sound in one frequency band impairs the perception of a useful sound in another band. This effect explains why external sounds interfere with speech even though they are in different frequencies. Masking models in hearing aids simulate heterophonic effects in order to optimally adjust compression and filters. Psychoacoustic tests quantify masking level differences. Understanding in noise improves when masking is specifically reduced.

Hidden hearing loss refers to synaptic damage between the inner hair cells and the auditory nerve that remains undetectable in standard audiograms. Affected persons complain of difficulties in understanding in noise, although the hearing thresholds are normal. The pathology manifests itself in reduced evoked potentials and altered OAEs. Research focuses on synaptoprotective therapies and early diagnosis. Hidden Hearing Loss emphasizes the importance of central auditory processing tests.

High-definition audiology combines high-resolution measurement techniques, adaptive signal processing and AI-supported analysis to revolutionize hearing diagnostics and hearing aid fitting. It uses detailed cochlear and cortex profiles to develop personalized amplification and compression strategies. Real-time data from mobile apps and biosensors flows into cloud-based fitting platforms. The aim is to maximize speech intelligibility and comfort in all hearing situations. Initial studies show significant improvements compared to standard methods.

A behind-the-ear (BTE) device places the electronics and battery behind the pinna, while a tube conducts sound to the earmold in the ear canal. This design allows powerful amplification and complex signal processors with low weight in the ear canal. BTE devices are robust, easy to use and suitable for moderate to severe hearing loss. Modern models integrate Bluetooth, telecoil and inductive charging functions. Feedback and sound quality can be individually controlled using open or closed earmolds.

A loss of high frequencies primarily affects the perception of high frequencies above around 2000 Hz. It often manifests itself in difficulties understanding consonants such as "s", "f" or "t", especially in noisy environments. The causes are usually noise damage, ageing processes or ototoxic drugs that damage hair cells in the basal cochlear region. Audiometrically, the loss manifests itself as an increase in the hearing threshold in the high frequencies. Hearing aid compression can specifically amplify the high frequency range in order to restore speech intelligibility.

The auditory pathway conducts acoustic information from the inner ear via several nuclei in the brain stem to the auditory cortex. It begins at the hair cells, runs via the vestibulocochlear nerve to the cochlear nucleus and further via the olive, lateral lemniscus and inferior colliculus to the thalamus. Each station extracts specific features such as time and level differences. Damage at any point leads to central auditory processing disorders. Objective evoked potentials (ABR, MLR, CAEP) test the integrity of the auditory pathway.

Auditory impression refers to the subjective perception of sound quality, volume and spatial position. It depends not only on acoustic parameters, but also on psychological factors such as attention and expectation. In audiology, hearing impression is measured using questionnaires and psychoacoustic tests. Hearing aid optimization aims to create a natural and pleasant auditory impression. Differences in hearing impression explain why people have different levels of satisfaction with hearing systems with identical measured values.

Hearing habituation describes the process of getting used to a new hearing aid or implant, as the brain has to process new sound patterns. Initially, many wearers find the amplified sounds too loud or unfamiliar. Through systematic wearing and targeted hearing training, the auditory cortex adapts and filters out unwanted parts. The weaning phase typically lasts several weeks to months. Accompanying audiological readjustment improves the success of adaptation and wearing comfort.

The auditory path depth is a measure of the temporal resolution of the auditory system, i.e. how closely successive sound events are still perceived as separate impulses. It is tested with short clicks or pulses and specified as the minimum interstimulus interval duration. Low auditory path depth makes it difficult to understand speech in impulsive noise. Measurements help to identify central temporal processing disorders. Auditory training can improve auditory pathway depth through neural plasticity.

Hearing feedback refers to feedback that hearing aid wearers sometimes perceive as an echo or whistling when the microphone signal reaches the receiver. This is caused by leaks in the earmold or incorrect amplification settings. Modern hearing systems detect feedback in real time and reduce it using adaptive filter algorithms. Mechanical measures such as tight earmoulds and microphone positioning minimize feedback risks. An optimized feedback manager increases sound quality and wearer satisfaction.

Hearing field analysis measures the hearing thresholds over a broad frequency and level spectrum to determine the individual dynamic range and comfort zone. It combines tone and loudness measurements and displays the results in hearing field curves. The analysis helps to determine optimum compression and amplification parameters for hearing aids. Deviations from the normal hearing field indicate bottlenecks in the perception of loudness and masking effects. Regular repetition documents progress in fitting.

A hearing filter selects certain frequency ranges to emphasize speech and suppress background noise. Hearing aids use digital multi-band filters that react adaptively to changes in the environment. Filter parameters such as center frequency, bandwidth and slope are individually adjusted. Incorrectly set filters can attenuate speech components or distort the sound. Psychoacoustic tests check filter effectiveness in real scenarios.

Hearing research comprises interdisciplinary studies on the mechanisms of hearing, diagnostic procedures and hearing aid technologies. It ranges from molecular studies of regenerative therapies to psychoacoustic experiments and clinical studies of new hearing aid algorithms. Current areas of focus are hidden hearing loss, AI-based signal processing and cochlear regeneration. Research results are incorporated into guidelines and product developments. International collaborations and publications ensure transfer into practice.

A hearing aid acoustician is a specialist who carries out hearing tests, fits and fine-tunes hearing aids. He advises on device types, earmolds and programs and trains wearers in their use and care. The training combines audiological, technical and communication skills. Quality assurance is achieved through validation tests and follow-up support. Good acousticians work closely with audiologists and ENT doctors.

Hearing aid batteries supply the electrical energy for analog and digital hearing systems. Common types are zinc-air cells (sizes 10, 13, 312, 675) with runtimes of 3-14 days. Rechargeable batteries are gaining in importance as they increase comfort and sustainability. Battery/charging cycles must be documented in order to avoid a drop in performance. Battery replacement training is part of hearing aid training.

The hearing aid channel is the device-specific frequency band in which a hearing aid amplifies or filters. Modern hearing aids have 4-16 channels to fine-tune the sound spectrum. More channels enable more precise fitting to the audiogram, but can increase computing power and latency. Channel parameters are visualized and optimized in the fitting software interface. However, the number of channels alone does not guarantee better speech intelligibility without correct fine-tuning.

A hearing aid program is a stored combination of settings for specific listening situations (e.g. quiet, restaurant, telephone). Programs automatically adapt amplification, compression and microphone characteristics to the ambient sound. Users switch manually or automatically via scene recognition. Diverse programs increase flexibility, but require training to use. Acoustician defines programs individually and calibrates transition parameters.

The provision of hearing aids includes selection, fitting, instruction and aftercare for hearing aid wearers. It begins with audiological diagnostics and continues with earmold production and fine-tuning in the real-life test. Regular checks ensure long-term function and satisfaction. Interdisciplinary cooperation with doctors and therapists optimizes rehabilitation. Documentation of all steps is part of the quality of care and cost coverage by insurance companies.

A hearing graph is the graphical representation of the audiogram and other measurement results such as OAE or reflexes in an overview. It visualizes hearing thresholds, dynamic range and comfort zones. Hearing graphs serve as a reference for fitting and progress checks. Software-generated graphs allow comparison of different measurement times. Clear visualization supports patients and professionals in discussions.

Hearing implants are electronic prostheses that convert acoustic information into electrical impulses and transmit them directly to the auditory nerve or brain stem. Types include cochlear implants, brainstem implants and bone conduction implants. Indications range from profound hearing loss to deaf inner ear. Implantation is performed surgically, followed by speech rehabilitation and mapping. Long-term success shows significant improvements in speech understanding and quality of life.

Auditory criticality describes the range around the hearing threshold in which small level changes are perceived particularly strongly. It is relevant for adjusting the compression so that signals remain natural and sound fluctuations remain audible. Measurements of the critical bandwidth provide information about filter design and masking effects. Narrower critical bands lead to better frequency selectivity. Fitting strategies in hearing aids take criticality into account to avoid sound coloration.

The auditory canal is the anatomical connection between the outer ear and the inner ear, consisting of the auditory canal, eardrum and ossicular chain. It transmits sound mechanically and optimizes impedance matching between the air and fluid medium. Diseases in this pathway (e.g. otosclerosis) lead to conductive hearing loss. Surgical procedures such as stapedotomy modify the auditory conduit to regain mobility. Tympanometry and audiogram analyze functional status.

Auditory localization is the ability to determine sound source direction based on interaural time differences (ITD) and level differences (ILD). The superior olivary complex in the brain stem compares signals from both ears. Precise localization improves speech comprehension and safety in everyday life. Hearing aids with binaural networking achieve localization by processing signals synchronously. Tests in the free sound field evaluate localization accuracy.

The auditory nerve (vestibulocochlear nerve, VIII cranial nerve) conducts electrical impulses from the cochlea and the vestibular organ to the brain stem. It branches into cochlear and vestibular parts and is essential for hearing and balance. Lesions lead to hearing loss, tinnitus or dizziness. Diagnostics include ABR measurements and imaging procedures. Early surgery is indicated for tumors such as acoustic neuroma.

In perceptual psychology, the horopter is the imaginary spatial curve on which visual and auditory stimuli are perceived as spatially congruent. With combined visual and acoustic stimulation, the horopter helps to minimize conflicts between eye and ear information. Experiments are being conducted to investigate how deviations from this line affect localization accuracy. For hearing aid wearers, the interaction of visual and auditory cues is relevant in order to precisely locate speech sources. Adaptations in hearing technology can aim to filter auditory signals so that they match the visual horopter.

Auditory pauses are deliberately inserted periods of silence between speech or music signals that give the auditory system time to process them. They improve speech comprehension by providing segmentation markers and enabling cognitive relief. In audiotherapy, listening breaks are used to provide tinnitus patients with periods of rest from the noise in their ears. Psychoacoustic studies show that regular breaks reduce auditory fatigue. Hearing aid programs can implement digital silence insertions to avoid excessive stimulation.

The hearing level refers to the sound pressure level at a specific point in the ear canal, measured in dB SPL. It is the basis for the calibration of audiometers and the adjustment of hearing aids. Differences between the input signal level and the hearing level in the earmold determine the effective amplification. In room acoustics, the hearing level is used to optimize volume distribution and sound quality. Audiologists make sure that hearing levels are below the comfort threshold and above the hearing threshold.

Hearing physiology describes the biological and biophysical processes from sound reception to neuronal processing in the brain. It includes mechanical processes in the outer ear, electrochemical transduction in hair cells and neuronal signal transmission. Changes in any of these steps lead to specific hearing disorders that can be analyzed physiologically. Research in hearing physiology provides the basis for therapies for hearing loss and tinnitus. Textbooks combine anatomy, biomechanics and neurophysiology into an integrative understanding.

Hearing preference refers to individual preferences for sound characteristics, such as warm bass or clear treble. It results from personal hearing adjustments and neurological processing differences. When fitting hearing aids, the preference is taken into account by fine-tuning the filters and compression parameters. Measurements are made by comparing different sound profiles and subjective rating. Good consideration of hearing preference increases wearing comfort and acceptance.

A listening test is a short sound or speech sequence that is used to test hearing aid programs or room acoustics. It is used by the wearer to assess the sound character and intelligibility under real conditions. In research, standardized auditory samples are used to compare the effects of signal processing algorithms. Audio samples can include music, speech or artificial test signals. Their systematic analysis helps to make optimizations.

Auditory noise is a uniform, broadband noise that is used as a test signal in audiometry to test masking and filtering effects. In tinnitus therapy, auditory noise is used as a masker to cover up ringing in the ears. The spectral composition can be white, pink or brown, depending on the desired masking effect. Auditory noise helps to analyze cochlear function and central noise processing. Customizable noise profiles support individual therapy goals.

Hearing cleaning refers to the professional removal of cerumen and deposits in the external auditory canal in order to restore sound conduction. It is carried out manually under a microscope or by means of gentle irrigation. Regular hearing cleaning prevents cerumen obturans and acute otitis externa. Subsequent tympanometry checks the restoration of middle ear function. Patients are trained in self-cleaning techniques to prevent recurrences.

The auditory quiet state is the state of minimal acoustic stimulation, usually measured in a soundproof room. It defines the baseline for hearing threshold tests and evoked potentials. A stable auditory quiet state ensures reproducible measurement results and avoids masking by ambient noise. Changes in the auditory quiet state can indicate adaptive processes or neuronal plasticity. Standardized norms define maximum background levels for test environments.

The hearing threshold is the lowest sound pressure level that can just be perceived and varies with frequency. It is documented individually for each frequency in the audiogram and forms the basis for diagnostics and hearing aid fitting. Deviations from normal values define degrees of hearing loss from mild to profound. Thresholds are determined using tone audiometry under controlled conditions. Clinically, it is the first step in differentiating between conductive and sensorineural hearing loss.

Auditory segmentation is the ability to break down continuous sound signals into meaningful units such as words or syllables. It is based on acoustic markers such as pauses, formant transitions and volume fluctuations. Disruptions in segmentation lead to speech comprehension difficulties, especially in noisy situations. Segmentation tests use sentences with variable pause patterns. Auditory training can improve segmentation performance in the auditory cortex.

The hearing range refers to the range between the quietest perceptible and the loudest tolerable sound intensity, measured in decibels. It represents the dynamic range of hearing and varies individually depending on age and hearing health. In normal hearing, the hearing range is typically between 0 dB HL and about 120 dB SPL. A restricted range requires compression in hearing aids to make soft sounds audible and loud sounds comfortable. Changes in hearing range can indicate conditions such as presbycusis or noise damage.

The hearing spectrum represents the distribution of the hearing threshold across the frequency spectrum and shows which frequencies are perceived how well. It is recorded in the audiogram as a curve from low to high frequencies. Deviations in certain areas indicate a loss of high or low frequencies. Hearing aids adjust amplification profiles along the spectrum to compensate for deficits. In research, hearing spectra from different populations are compared to determine normal values and risk factors.

The audio track is the acoustic accompaniment to video or multimedia content and contains speech, music and effects. For accessible content, it is often supplemented with subtitles or sign language. Technically, the audio track is mixed in multi-channel audio (stereo, 5.1) to create spatial effects. In hearing training and rehabilitation, listening to individual tracks can train speech comprehension. For hearing aids with direct streaming, the audio track is transmitted to the device digitally and without interference.

A sudden hearing loss is a sudden onset, usually one-sided sensorineural hearing loss, often accompanied by tinnitus and a feeling of pressure. The exact causes are unclear, possible factors are circulatory disorders, viruses or stress. Immediate therapy with corticosteroids and blood circulation stimulants improves the chances of recovery. Audiometry documents the extent of hearing loss, follow-up checks show regeneration. Early rehabilitation can compensate for residual hearing loss and alleviate tinnitus.

A hearing system is a combination of hearing aid, earmold and optional accessory components such as an FM receiver or streamer. It comprises microphones, amplifiers, signal processors and receivers in a coordinated ensemble. Modern systems offer multi-channel compression, directional microphones, feedback management and wireless connectivity. Fitting is carried out individually by the acoustician based on the audiogram and personal hearing preferences. Regular software updates maintain performance and compatibility with new devices.

Hearing technology encompasses all technical aids and procedures for improving hearing, from hearing aids and cochlear implants to room and sound technology. It combines acoustics, electronics and signal processing to optimize speech intelligibility and sound quality. The sub-disciplines include microphone design, amplifier architecture, filter algorithms and user interfaces. Hearing technology research is driving developments such as AI-supported scene recognition and brain-computer interfaces. Users benefit from customizable, networked systems for all areas of life.

Hearing loss refers to a reduction in hearing ability, subdivided into conductive, sensorineural and central hearing disorders. It is quantified on the basis of the shift in the hearing threshold in the audiogram. Causes include age, noise, illness or genetic factors. Treatment options range from hearing aids and implants to medication and surgery. Early detection and interdisciplinary rehabilitation improve communication skills and quality of life.

Hearing ability encompasses the entire ability to detect and localize sound sources and process acoustic information. It includes parameters such as hearing threshold, dynamic range, frequency resolution and speech comprehension. Measurement methods such as audiogram, OAE and AEP provide objective data on hearing ability. Psychometric tests record subjective aspects such as hearing comfort and hearing strain. Maintaining and improving hearing ability are central goals of audiology and hearing acoustics.

The auditory center in the temporal lobe of the cerebral cortex (primary auditory cortex) processes the frequency, volume and spatial characteristics of sound. It receives input via the auditory pathway and interacts with speech and memory centers. Cortical plasticity enables adaptation to hearing aids and rehabilitation after hearing loss. Lesions in the auditory center lead to central auditory processing disorders despite an intact peripheral device. Imaging techniques (fMRI, PET) show activation patterns during acoustic tasks.

Hospitalism describes psychological and cognitive impairments that arise as a result of sensorineural hearing loss due to social isolation and loss of communication. Those affected often develop anxiety, depression and withdrawal, which further exacerbates the hearing loss. Early psychosocial interventions and hearing rehabilitation prevent hospitalization. Interdisciplinary care by audiologists, psychologists and social workers is important. Studies show that social support and hearing aid provision significantly reduce hospitalization.

Hyperacusis is a hypersensitivity to normal everyday sounds that are perceived as painful or unpleasant. It is caused by changes in peripheral or central auditory pathways, often in combination with tinnitus. Comfort and discomfort thresholds are determined diagnostically. Therapy includes desensitization training, cognitive behavioural therapy and, if necessary, medication. Hyperacusis can severely restrict quality of life and requires multidisciplinary care.